You're not able to do that just yet. In order to close the thread you need to be a Premium user, the folks with the red names, and to delete posts you need to be a Platinum, what I am. You don't get to Premium until you get 1000 posts and Platinum at 3000. So the most you could do is ask a mod to delete it for you. Or just close it. I would suggest either Takushi Rena or Orion. They both have power in the RP section.
As for the tavern, it's just a place for people to go and discuss new RPs. Some just post that they created one with a link. Same thing with a thread in the main RP section.